#include <cstdlib>
#include <cmath>
#include <climits>
#include <functional>
#include <algorithm>

#include <cubescript/cubescript.hh>

namespace cubescript {

static constexpr float_type PI = 3.14159265358979f;
static constexpr float_type RAD = PI / 180.0f;

template<typename T>
struct math_val;

template<>
struct math_val<integer_type> {
    static integer_type get(any_value &tv) {
        return tv.get_int();
    }
    static void set(any_value &res, integer_type val) {
        res.set_int(val);
    }
};

template<>
struct math_val<float_type> {
    static float_type get(any_value &tv) {
        return tv.get_float();
    }
    static void set(any_value &res, float_type val) {
        res.set_float(val);
    }
};

template<typename T>
struct math_noop {
    T operator()(T arg) {
        return arg;
    }
};

template<typename T, typename F1, typename F2>
static inline void math_op(
    std::span<any_value> args, any_value &res, T initval,
    F1 binop, F2 unop
) {
    T val;
    if (args.size() >= 2) {
        val = binop(math_val<T>::get(args[0]), math_val<T>::get(args[1]));
        for (size_t i = 2; i < args.size(); ++i) {
            val = binop(val, math_val<T>::get(args[i]));
        }
    } else {
        val = unop(!args.empty() ? math_val<T>::get(args[0]) : initval);
    }
    math_val<T>::set(res, val);
}

template<typename T, typename F>
static inline void cmp_op(std::span<any_value> args, any_value &res, F cmp) {
    bool val;
    if (args.size() >= 2) {
        val = cmp(math_val<T>::get(args[0]), math_val<T>::get(args[1]));
        for (size_t i = 2; (i < args.size()) && val; ++i) {
            val = cmp(math_val<T>::get(args[i - 1]), math_val<T>::get(args[i]));
        }
    } else {
        val = cmp(!args.empty() ? math_val<T>::get(args[0]) : T(0), T(0));
    }
    res.set_int(integer_type(val));
}

void init_lib_math(state &cs) {
    cs.new_command("sin", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::sin(args[0].get_float() * RAD));
    });
    cs.new_command("cos", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::cos(args[0].get_float() * RAD));
    });
    cs.new_command("tan", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::tan(args[0].get_float() * RAD));
    });

    cs.new_command("asin", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::asin(args[0].get_float()) / RAD);
    });
    cs.new_command("acos", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::acos(args[0].get_float()) / RAD);
    });
    cs.new_command("atan", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::atan(args[0].get_float()) / RAD);
    });
    cs.new_command("atan2", "ff", [](auto &, auto args, auto &res) {
        res.set_float(std::atan2(args[0].get_float(), args[1].get_float()) / RAD);
    });

    cs.new_command("sqrt", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::sqrt(args[0].get_float()));
    });
    cs.new_command("loge", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::log(args[0].get_float()));
    });
    cs.new_command("log2", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::log(args[0].get_float()) / M_LN2);
    });
    cs.new_command("log10", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::log10(args[0].get_float()));
    });

    cs.new_command("exp", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::exp(args[0].get_float()));
    });

    cs.new_command("min", "i1V", [](auto &, auto args, auto &res) {
        integer_type v = (!args.empty() ? args[0].get_int() : 0);
        for (size_t i = 1; i < args.size(); ++i) {
            v = std::min(v, args[i].get_int());
        }
        res.set_int(v);
    });
    cs.new_command("max", "i1V", [](auto &, auto args, auto &res) {
        integer_type v = (!args.empty() ? args[0].get_int() : 0);
        for (size_t i = 1; i < args.size(); ++i) {
            v = std::max(v, args[i].get_int());
        }
        res.set_int(v);
    });
    cs.new_command("minf", "f1V", [](auto &, auto args, auto &res) {
        float_type v = (!args.empty() ? args[0].get_float() : 0);
        for (size_t i = 1; i < args.size(); ++i) {
            v = std::min(v, args[i].get_float());
        }
        res.set_float(v);
    });
    cs.new_command("maxf", "f1V", [](auto &, auto args, auto &res) {
        float_type v = (!args.empty() ? args[0].get_float() : 0);
        for (size_t i = 1; i < args.size(); ++i) {
            v = std::max(v, args[i].get_float());
        }
        res.set_float(v);
    });

    cs.new_command("abs", "i", [](auto &, auto args, auto &res) {
        res.set_int(std::abs(args[0].get_int()));
    });
    cs.new_command("absf", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::abs(args[0].get_float()));
    });

    cs.new_command("floor", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::floor(args[0].get_float()));
    });
    cs.new_command("ceil", "f", [](auto &, auto args, auto &res) {
        res.set_float(std::ceil(args[0].get_float()));
    });

    cs.new_command("round", "ff", [](auto &, auto args, auto &res) {
        float_type step = args[1].get_float();
        float_type r = args[0].get_float();
        if (step > 0) {
            r += step * ((r < 0) ? -0.5 : 0.5);
            r -= std::fmod(r, step);
        } else {
            r = (r < 0) ? std::ceil(r - 0.5) : std::floor(r + 0.5);
        }
        res.set_float(r);
    });

    cs.new_command("+", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(args, res, 0, std::plus<integer_type>(), math_noop<integer_type>());
    });
    cs.new_command("*", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 1, std::multiplies<integer_type>(), math_noop<integer_type>()
        );
    });
    cs.new_command("-", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, std::minus<integer_type>(), std::negate<integer_type>()
        );
    });

    cs.new_command("^", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, std::bit_xor<integer_type>(), [](integer_type val) { return ~val; }
        );
    });
    cs.new_command("~", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, std::bit_xor<integer_type>(), [](integer_type val) { return ~val; }
        );
    });
    cs.new_command("&", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, std::bit_and<integer_type>(), math_noop<integer_type>()
        );
    });
    cs.new_command("|", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, std::bit_or<integer_type>(), math_noop<integer_type>()
        );
    });

    /* special combined cases */
    cs.new_command("^~", "i1V", [](auto &, auto args, auto &res) {
        integer_type val;
        if (args.size() >= 2) {
            val = args[0].get_int() ^ ~args[1].get_int();
            for (size_t i = 2; i < args.size(); ++i) {
                val ^= ~args[i].get_int();
            }
        } else {
            val = !args.empty() ? args[0].get_int() : 0;
        }
        res.set_int(val);
    });
    cs.new_command("&~", "i1V", [](auto &, auto args, auto &res) {
        integer_type val;
        if (args.size() >= 2) {
            val = args[0].get_int() & ~args[1].get_int();
            for (size_t i = 2; i < args.size(); ++i) {
                val &= ~args[i].get_int();
            }
        } else {
            val = !args.empty() ? args[0].get_int() : 0;
        }
        res.set_int(val);
    });
    cs.new_command("|~", "i1V", [](auto &, auto args, auto &res) {
        integer_type val;
        if (args.size() >= 2) {
            val = args[0].get_int() | ~args[1].get_int();
            for (size_t i = 2; i < args.size(); ++i) {
                val |= ~args[i].get_int();
            }
        } else {
            val = !args.empty() ? args[0].get_int() : 0;
        }
        res.set_int(val);
    });

    cs.new_command("<<", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, [](integer_type val1, integer_type val2) {
                return (val2 < integer_type(sizeof(integer_type) * CHAR_BIT))
                    ? (val1 << std::max(val2, integer_type(0)))
                    : 0;
            }, math_noop<integer_type>()
        );
    });
    cs.new_command(">>", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, [](integer_type val1, integer_type val2) {
                return val1 >> std::clamp(
                    val2, integer_type(0), integer_type(sizeof(integer_type) * CHAR_BIT)
                );
            }, math_noop<integer_type>()
        );
    });

    cs.new_command("+f", "f1V", [](auto &, auto args, auto &res) {
        math_op<float_type>(
            args, res, 0, std::plus<float_type>(), math_noop<float_type>()
        );
    });
    cs.new_command("*f", "f1V", [](auto &, auto args, auto &res) {
        math_op<float_type>(
            args, res, 1, std::multiplies<float_type>(), math_noop<float_type>()
        );
    });
    cs.new_command("-f", "f1V", [](auto &, auto args, auto &res) {
        math_op<float_type>(
            args, res, 0, std::minus<float_type>(), std::negate<float_type>()
        );
    });

    cs.new_command("div", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, [](integer_type val1, integer_type val2) {
                if (val2) {
                    return val1 / val2;
                }
                return integer_type(0);
            }, math_noop<integer_type>()
        );
    });
    cs.new_command("mod", "i1V", [](auto &, auto args, auto &res) {
        math_op<integer_type>(
            args, res, 0, [](integer_type val1, integer_type val2) {
                if (val2) {
                    return val1 % val2;
                }
                return integer_type(0);
            }, math_noop<integer_type>()
        );
    });
    cs.new_command("divf", "f1V", [](auto &, auto args, auto &res) {
        math_op<float_type>(
            args, res, 0, [](float_type val1, float_type val2) {
                if (val2) {
                    return val1 / val2;
                }
                return float_type(0);
            }, math_noop<float_type>()
        );
    });
    cs.new_command("modf", "f1V", [](auto &, auto args, auto &res) {
        math_op<float_type>(
            args, res, 0, [](float_type val1, float_type val2) {
                if (val2) {
                    return float_type(fmod(val1, val2));
                }
                return float_type(0);
            }, math_noop<float_type>()
        );
    });

    cs.new_command("pow", "f1V", [](auto &, auto args, auto &res) {
        math_op<float_type>(
            args, res, 0, [](float_type val1, float_type val2) {
                return float_type(pow(val1, val2));
            }, math_noop<float_type>()
        );
    });

    cs.new_command("=", "i1V", [](auto &, auto args, auto &res) {
        cmp_op<integer_type>(args, res, std::equal_to<integer_type>());
    });
    cs.new_command("!=", "i1V", [](auto &, auto args, auto &res) {
        cmp_op<integer_type>(args, res, std::not_equal_to<integer_type>());
    });
    cs.new_command("<", "i1V", [](auto &, auto args, auto &res) {
        cmp_op<integer_type>(args, res, std::less<integer_type>());
    });
    cs.new_command(">", "i1V", [](auto &, auto args, auto &res) {
        cmp_op<integer_type>(args, res, std::greater<integer_type>());
    });
    cs.new_command("<=", "i1V", [](auto &, auto args, auto &res) {
        cmp_op<integer_type>(args, res, std::less_equal<integer_type>());
    });
    cs.new_command(">=", "i1V", [](auto &, auto args, auto &res) {
        cmp_op<integer_type>(args, res, std::greater_equal<integer_type>());
    });

    cs.new_command("=f", "f1V", [](auto &, auto args, auto &res) {
        cmp_op<float_type>(args, res, std::equal_to<float_type>());
    });
    cs.new_command("!=f", "f1V", [](auto &, auto args, auto &res) {
        cmp_op<float_type>(args, res, std::not_equal_to<float_type>());
    });
    cs.new_command("<f", "f1V", [](auto &, auto args, auto &res) {
        cmp_op<float_type>(args, res, std::less<float_type>());
    });
    cs.new_command(">f", "f1V", [](auto &, auto args, auto &res) {
        cmp_op<float_type>(args, res, std::greater<float_type>());
    });
    cs.new_command("<=f", "f1V", [](auto &, auto args, auto &res) {
        cmp_op<float_type>(args, res, std::less_equal<float_type>());
    });
    cs.new_command(">=f", "f1V", [](auto &, auto args, auto &res) {
        cmp_op<float_type>(args, res, std::greater_equal<float_type>());
    });
}

} /* namespace cubescript */